1. Field of the Invention
This invention relates to apparatus for forming a flexible tubing from a single-ply or multiply web as it is continuously advanced, comprising two size-defining metal plates, which define the width of the flattened tubing and are substantially parallel to each other and are movably mounted in the machine frame and have receiving or upstream end portions about which the web is deflected to raise edge portions of the web which are to be infolded to overlap each other, and which plates are adjustable by a screw or the like to control the distance between their receiving end portions, whereas the plates are provided at their delivery or downstream end portions with straps or the like for controlling the distance between the plates.
2. Description of the Prior Art
German Patent Specification No. 11 62 544, expressly incorporated herein by reference, discloses such an apparatus, which is usually described as a tubing-forming station in machines for making flexible tubing. In German Patent Specification No. 11 62 544 it has not been stated how delivery end portions of the size-defining plates are fixed in their adjusted position. In apparatus of the known kind the delivery end portions of the size-defining plates are usually interconnected by straps, which can be fixed in an adjusted position by screw means. If the distance between the delivery end portions of the size-defining plates is to be corrected because a different size has been selected, the feeding of the web must be interrupted and the screw means must be loosened and must be re-tightened after the adjustment to the new position. Such complicated and time-consuming adjusting work involving a standstill of the machine may have to be performed several times.